Effects of mercury and probiotics on the microbiome and behavior of the prairie vole (Microtus ochrogaster)

Abstract

The digestive tract is home to trillions of microorganisms. In addition to helping with digestion, these microbes can have profound effects on host mood and behavior through a pathway known as the microbiome-gut-brain axis. By this pathway, changes in the intestinal microbial community can alter anxiety behaviors, depression, and sociability.

The aim of the current study was to characterize the impacts of mercury exposure and probiotic administration on both the gut microbiome and the anxiety and social behaviors of the prairie vole (Microtus ochrogaster). Following four weeks of exposure to 60 ppm mercuric chloride (HgCl2), anxiety-like behaviors were significantly elevated in the voles. Subsequent administration of a potentially-probiotic Lactobacillus suspension (3.8 x 108 CFU / ml) for two weeks was not effective at remediating anxiety behaviors or the previously-reported decrease in sociability.

Microbiome analysis revealed significant changes in the microbial communities in response to mercury exposure and the administration of both the Lactobacillus suspension and its resuspension agent alone (0.15% maltodextrin). Several microorganisms were also correlated with specific anxiety and social behaviors, highlighting the strong possibility of microbiome-gut-brain axis involvement in changes in these behaviors.

Overall, the current study provides clarity into the impacts of mercury and probiotics on the microbial community and identifies several specific microorganisms that may alter prairie vole behavior via the microbiome-gut-brain axis.